Add a method to tab_utils.h to find out whether a tab is playing audio.

chrome/chrome_browser.gypi

 # Copyright 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 1005 matching lines @@
         'browser/managed_mode/managed_mode_resource_throttle.cc',
         'browser/managed_mode/managed_mode_resource_throttle.h',
         'browser/managed_mode/managed_mode_site_list.cc',
         'browser/managed_mode/managed_mode_site_list.h',
         'browser/managed_mode/managed_mode_url_filter.cc',
         'browser/managed_mode/managed_mode_url_filter.h',
         'browser/managed_mode/managed_user_service.cc',
         'browser/managed_mode/managed_user_service.h',
         'browser/managed_mode/managed_user_service_factory.cc',
         'browser/managed_mode/managed_user_service_factory.h',
+        'browser/media/audio_stream_indicator.cc',
+        'browser/media/audio_stream_indicator.h',
         'browser/media/media_capture_devices_dispatcher.cc',
         'browser/media/media_capture_devices_dispatcher.h',
         'browser/media/media_stream_capture_indicator.cc',
         'browser/media/media_stream_capture_indicator.h',
         'browser/media/media_stream_devices_controller.cc',
         'browser/media/media_stream_devices_controller.h',
         'browser/media_gallery/linux/mtp_device_delegate_impl_linux.cc',
         'browser/media_gallery/linux/mtp_device_delegate_impl_linux.h',
         'browser/media_gallery/linux/mtp_device_object_enumerator.cc',
         'browser/media_gallery/linux/mtp_device_object_enumerator.h',
@@ skipping 2090 matching lines @@
           'variables': {
             'jni_gen_dir': 'chrome',
           },
           'includes': [ '../build/jni_generator.gypi' ],
         },
       ],
      },
     ],
   ],
 }